The WPB Cuben abrasion resistance is projected to be lower than 3 layer eVent because there is not a tricot layer on either side. See my eVent and 2011 version WPB Cuben micrographs in submission 45 – 47 shown at http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=45026&disable_pagination=1 .

My tests and micrographs suggest to me (not proves) that the 2013 dotted WPB Cuben uses MP PU forced through one side of the Dyneema fibers and then scraped (mechanically abraded) into a square pattern on the forcing side, rather than eVent membranes on two sides. An alternative explanation is that after lamination, they mechanically abraded the eVent membranes to have a checkerboard pattern with the double thickness membranes only remaining on the perimeters of the abraded areas. In either case, the fabrication methodology looks very similar to 2011 submission 47 using non-MP PU.

The areal density of the sample I tested was 58.14 g/m2 (1.71 oz/yd2). The areal density spec is (48.3 g/m²) 1.42 oz/yd2. The HH tested greater than 3,515 mm H2O.

The following micrographs list the field of view (horizontal distance) and illumination source (top of sample or bottom of sample).

1 - 20mm BottomThis micrograph best illustrates the fabrication sandwich which is made up of two WPB layers each with a thickness of .027 mm sandwiched on either side of a Dyneema matrix-like-pattern with a thickness of .021mm. I measured the thickness of each layer in my lab. The major grids are formed from a thicker WPB material rather than thicker Dyneema fibers.

1 - 20mm TopThe manufacturing abrasion patterns are not the same on both sides of the fabric. This is the side opposite of what is shown in the prior micrograph. Note there is no tricot layer to protect the WPB layer on either side from field use abrasion as is commonly provided with conventional eVent fabrications.

Thank you for the report Richard. If i had bought some of this gear, i might be a little bummed with these results. That level of breathability is nothing to write home about.

Do you think anyone will ever do anything with pure UHMWPE fiber fabrics? Or are there inherent limitations with using this fiber in a woven forms? I've read that the fibers are so slippery that they do not stay put well in a weave or knit form, BUT i have some 100% woven dyneema sleeves which are holding up just fine... so i'm not sure what to believe.

ps... really quickly... would like to address/bounce this one thing off you...

I think the really interesting part of this was the statement:

the fabrication sandwich which is made up of two WPB layers {eVENT} each with a thickness of .027 mm sandwiched between a Dyneema

As I read it, you are saying that it is two layers of eVENT INSIDE of a spliced-open piece of Dyneema (thus-three layer... it would be four layers if the Dyneema were literally on both sides and the Dyneema was not spliced-open, right?)... anyway...

that goes against all we have been told about this fabric... as Joe has written on the zpacks website, and been told by CTC:

the fabric is a three layer laminate with high strength Dyneema fibers sandwiched between eVent

I was incorrect when I said, "the fabrication sandwich which is made up of two WPB layers {eVENT} each with a thickness of .027 mm sandwiched between a Dyneema" I will update the original post. The Dyneema is in the middle.

richard, Thanks for doing this test. It confirms what I was expecting.

I have a westcomb specter Lt Event jacket. The pockets in this jacket were made by stitching two pieces of Event fabric together. This portion of my jacket is the only location where condensation has occured in my earlier testing (It has been very dry in California since then so it hasn't gotten much use on the trail}. Unzipping the pockets helps but 2 layers of Event is not nearly as good as a single layer.

Two layers means:1 It takes longer for air to work its way through meaning less moisture is carried away.2. Zpacks must use some sort of glue to bond the two layers of Event membrane to the fabric in the middle. The glue can cover some of the microscopic holes in the membrane further reducing breath ability.

Zpacks would have done better it the cuben was one the outside with one layer of Event membrane was on the inside surface.

Zpacks must use some sort of glue to bond the two layers of Event membrane to the fabric in the middle ... Zpacks would have done better it the cuben was one the outside with one layer of Event membrane was on the inside surface.

Uhh, ZPacks has nothing to do with fabric manufacturing. No more than NW Alpine does with their jacket that uses this same fabric. These two companies just make the garments with the fabric that CTC supplies them.

Your empirical evidence supports the less scientific "bubbler" test that Prolitegear did - this new fabric is excellent from a weight standpoint but its breathability is not impressive. Too bad, but just what I was afraid of.

My confusion stems from this--my understanding is that low cost micro porous PU coatings have been around for awhile, and have been considered "poor" in the breath-ability/air permeability department for awhile.

Then, comparing that to average 3 layer UL eVent material, by the numbers it seems that these are roughly 3 times more air permeable than the cuben-eVent and the PU stuff, which in my mind is a considerable difference.

"Then, comparing that to average 3 layer UL eVent material, by the numbers it seems that these are roughly 3 times more air permeable than the cuben-eVent and the PU stuff, which in my mind is a considerable difference."